Could someone help me. I went to turn on my sprinkler system for the first time after it was winterized. I slowly opened the main water valve and started a program on the controller and nothing works. I hear a buzzing sound in valve box.

There are two valves that I can open and close on the backflow preventer. When I open them, the water goes to the sprinkler heads, but also sprays out of two open female threaded connections on the backflow preventer. Should these openings be plugged? I had no problems starting the system last year. I wonder if the company that winterized the system screwed something up.

Thanks in advance for your help